I don’t feel motivated or inspired to do anything.
That’s tough. I find that I tend to feel more motivated once I actually force myself to start something. Maybe try keeping a consistent sleep schedule and getting up early to work on learning something new, like a hobby or a language. Often, once you start doing something like that, you feel a sense of accomplishment that keeps you motivated to continue. Getting started can be tough though.
And if you don’t mind me saying this, for the sake of being fully honest about what I think part of your problem is, I truly believe we are all ultimately made for God, which means that we can never find complete fulfillment without Him. At least that’s my own experience and that of the people I know.